Hydraulic arrangements that are used for locking implements to wheeled loaders, such as telescopic loaders or front loaders, are known per se. To this end, hydraulic cylinders are employed as locking cylinders so that the implements can be mounted hydraulically to the tool carriers of the loader. The control of the locking cylinders on the tool carrier, which are used, for example, to attach tools such as buckets, is carried out, for example, via manually actuated 6/2-way valves, which allow the locking cylinders to be connected and disconnected. The 6/2-way valves are disposed such that no other hydraulic functions on the tool can be actuated at the same time. Only by switching the 6/2-way valve to the second position can the tool be actuated, however at the same time the hydraulic supply to the locking cylinder is interrupted. An operator will quickly notice that he/she forgot something when he/she attempts to actuate a hydraulic function on the tool and the 6/2-way valve has not assumed the second position. A hydraulic arrangement of this type, however, is associated with the risk of forgetting to lock the locking cylinder and engage the second position for operating the tool. The tool may suddenly drop, for example when emptying a bucket, which is a serious safety risk. Furthermore these 6/2-way valves are more expensive compared to simpler control valves.
Additionally, it is known to operate hydraulic arrangements of this type with a ball valve instead of the manually actuated 6/2-way valve. The operator has to close this ball valve after the locking cylinder has been extended for locking purposes. It is necessary to close the ball valve to ensure that during faulty operation of the hydraulic control devices the locking cylinders are not accidentally unlocked and that consequently a tool can become detached from the tool carrier and fall to the ground. This, however, is possible when the ball valves are open and represents a corresponding potential for faulty operation. Additionally, it is disadvantageous that an operator is able to actuate all other additional hydraulic functions on the tool, even if the ball valve is not closed.